[Not agreeing with actions that took place in the past, aside, he honestly isn't judging Spike for much at all. Sure, he can be exasperating, but Zero doesn't straight up hate him for anything. There's no reason to; it takes a whole hell of a lot for him to straight up hate someone. He also couldn't care less what Spike thinks of him, in turn, but all of that has already been said and done.]
Which is no real surprise. Although there is a class, the purebloods, who can control that sort of thing. They can wholly bind the lower level vampires, and humans, alike, to their will. Even compelling them to take their own lives. They also are the only ones capable of turning people into vampires. It's when the turn isn't completed do those aforementioned no sense of self vampires come from.